Day1.java

package aoc2023;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Map;    

public class Day1 {

	public static void main(String[] args) throws Exception 
	{
		part1();
		part2();
	}

	private static void part1() throws IOException {
		int sum = Files
			.readAllLines(Path.of("input1.txt"))
			.stream()
			.map(s -> s.replaceAll("\\D+",""))
			.mapToInt(s -> Integer.parseInt(s.charAt(0)+""+s.charAt(s.length()-1)))
			.sum();

		System.out.println(sum);
	}

	static Map<String, String> numbers = Map.of(
		"one", "1", 
		"two", "2",  
		"three", "3", 
		"four", "4",
		"five", "5",
		"six", "6",  
		"seven", "7", 
		"eight", "8",
		"nine", "9"
	) ;
	
	private static String extractNumbers(String in)
	{
		String out = "";
		
		for (int i = 0; i < in.length(); i++) 
			if(Character.isDigit(in.charAt(i)))
				out+=in.charAt(i);
			else
				for (var e : numbers.entrySet()) 
					if(in.indexOf(e.getKey(), i) == i) 					
						out+=e.getValue();
			
		return out;
	}
	
	private static void part2() throws IOException {
		int sum = Files
			.readAllLines(Path.of("input1.txt"))
			.stream()
			.map(Day1::extractNumbers)
			.mapToInt(s -> Integer.parseInt(s.charAt(0)+""+s.charAt(s.length()-1)))
			.sum();

		System.out.println(sum);
	}

}